Delivery trucks are typically heavy, diesel-burning beasts that churn out clouds of exhaust – not the greatest thing for the environment. But if grocery-store owners and consumers were to use them smartly, these boxy vehicles might in fact reduce greenhouse-gas emissions, according to new research.

The climate-changing qualities of services like FreshDirect, Peapod and Google's trial project in San Francisco are the subject of a recent study by Anne Goodchild and Erica Wygonik, engineers at the University of Washington. They found that the traditional method of grocery shopping in America – driving to and from a store – is much less friendly to the overheated atmosphere than simply ordering the supplies online. The difference they detected is stark: Going the delivery truck-route reduced CO2 emissions by at least half in their model, compared to car trips.

(Goodchild/Wygonik)

The study focused on a traffic simulation of Seattle whose imaginary citizens shopped at whatever market was closest to them. By cutting off their ability to get behind the wheel and forcing them to receive Kashi and kale from delivery services instead, the researchers estimated that 20 to 75 percent less CO2 made its way into the air. The amount of tummy fat grew by .01 percent as a result of not walking through the aisles – that's just my guess – but hey, going green requires sacrifices. As one of the engineers put it, "A lot of times people think they have to inconvenience themselves to be greener, and that actually isn’t the case here."

Companies also would be wise to establish set routes for their delivery trucks that go through densely packed clumps of customers, the researchers found:

They also discovered significant savings for companies – 80 to 90 percent less carbon dioxide emitted – if they delivered based on routes that clustered customers together, instead of catering to individual household requests for specific delivery times.

“What’s good for the bottom line of the delivery service provider is generally going to be good for the environment, because fuel is such a big contributor to operating costs and greenhouse gas emissions,” Wygonik said. “Saving fuel saves money, which also saves on emissions.”

Given its impact on emissions, the government might consider subsidizing online-food shopping in some way, the engineers say. Consider reading the long, full study as it appears in the Journal of the Transportation Research Forum, if you're limboing in that two-hour time window it takes for a grocery truck to arrive.

Top image: A "Now Hiring" sign is seen on the back of a Fresh Direct grocery delivery truck in New York City. (Lucas Jackson/Reuters)